Furniture W&M simplifications

[MikeJohns]

When designing a private sailing vessel and it comes to do the weights and moments calculations, I was wondering what others do with the interior fit-out.

Do you all take every furniture item throughout the vessel from the sock drawer in the aft cabin to the soap locker in the fwd head.
Or do you simplify and use a few rules of thumb?

It seems to me that on a heavier displacement vessel the fitout could be gerneralised in the W&M calcs.

Mike

It is a very tediuos job indeed. That moments spreadsheet grows and grows as you remember things. But it must be done. I generalise from past designs for the initial design up to acceptance from the client. Then the hired help (read junoir designer) enters every bench top drawer and tap even on large boat designs.

The fitout on one recent 46 footer exceeded one tonne for soles ceiling and furniture (lots of hardwood) quickly looking at its vital statistics the furniture mass centroid was located well aft.

If you do a full analysis it means the trimmer ballast is kept very much to a minimum and you can provide a full spec to the builder.

Other designers have succesfully generalised based on previous work when designing similar vessels. Others have not been so successfull with large amounts of trim ballast detrimentally in the ends.

Michael

[MikeJohns]

Thanks for your post

Yep the old trimmer ballast trick....keep 5 tonnes of ballast out of the keel so you can stick it in the focsle if required !
That approach tends to go along with cheap sets of plans.

I know all the ins and outs, I was just interested in what other designers do.

Inded the spreadsheet for mass-moments gets very long and we have no juniors like you to do the tedius bits. Who checks the juniors work?

[mistral]

I'm just a beginner in boat design; I usually go for a first step design in which i consider a stock value of all the furnitures based on the boat lenght and type (cruiser, racer), I do almost the same thing for deck gear; in a second step of design, detailing the weight of the boat and her balance, you have to do a complete list of everything is on board and where is located, in order to have a correct evaluation of weights and balance and calculate real CG of the boat; it's a very boring job and spreadsheet grows longer and wider but you can't avoid it :-((((

fair wind
Mistral